Considering that Microsoft has yet to be a real friend to open source I have to be at least a bit suspect of the intentions behind the sponsorship of the ongoing open source census.
My guess? I think Microsoft wants access to the results both so it can understand open source but also so it can start to consider legal actions against the most popular products and the companies that develop them.
I'll apologize in advance if the motives are completely altruistic but if the past is any evidence, we should really avoid giving this kind of information to Microsoft with no benefits attached to open source.
The company's "customers, partners and developers are working in increasingly heterogeneous environments," so participation in projects such as the census is relevant to the "ecosystem" in which Microsoft operates, said Sam Ramji, Microsoft's senior director of platform strategy, in a prepared statement.
I, along with many others in the open source vendor and developer community have met with Sam and I think we all believe he has good intentions, but it's still Microsoft and needs to be taken with a grain of salt.